This is a 93 Dakota 3.9L Electronic spark timing.
Scope pattern anylyst needed
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Hi I have had a look at the engine, its a V6 with a distributor fitted into the rear of the V section. Are you sure the distributor even though having electronic control does not have centrifugal weights fitted under the base plate for ignition advance?
DavidComment
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I first want to say I in no way consider myself an expert at wave form analysis, I'm just a guy who experiments and practices alot. Any time I check an electrical device with windings (motors, relays, solenoids, coils) I want to see what they look like from a voltage veiw(back probe) and amperage(current ramp with a low amp probe). That being said I would check the coil with just one channel turned on. If useing a back probe set it to about a 50 ms sweep and 100 volts and adjust it from there so you can see all six cylinders firing and compare, maybe trigger off an injector so you know whats what, to me what you provided almost looks like you had channel 3 inverted, not sure. If the cam crank sync was off or one of the signals lost you should be able to see that by graphing that on the scanner side so just concentrate on checking the ignition with the scope for now. The ignition module is part of the PCM so you want to make sure all your grounds are good by checking voltage drop. Also maybe disconnect the alternator. A resistance check of the coil may be useful but current ramping is prefered. good luck And report back with what you find.Attached FilesComment
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Got it
Got it, I first changed the crank sensor because the waveform didn't match any know good that I could find, but never changed when problem occured. New crank sensor no difference. So I then tried a second PCM and nailed it finally. I want to greatly thank everyone that helped. I've learned alot, how to take and post a snapshot and to keep a library of known good waveforms.
Thank youComment
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nailed it
Got it, I first changed the crank sensor because the waveform didn't match any know good that I could find, but never changed when problem occured. New crank sensor no difference. So I then tried a second PCM and nailed it finally. I want to greatly thank everyone that helped. I've learned alot, how to take and post a snapshot and to keep a library of known good waveforms.
Thank youComment
Comment